1. Field of the Invention:
This invention relates to heat exchangers, and more particularly, to a temperature controller which varies the effective heat transfer surface of the heat exchanger.
2. Description of the Prior Art:
The demand for electrical power in the United States approximately doubles every ten years. Presently, fossil fuels provide a majority of the heat energy needed to produce electrical power. However, in the next thirty years, it is estimated that over fifty percent of our electrical energy will be produced utilizing heat resulting from nuclear reactions. Fusion nuclear reactions are not commercially available and the supply of fissionable material is limited, so that future nuclear power plants depend on developing economical fast breeder reactors which produce more fissionable material than they consume. To produce economical and reliable liquid metal fast breeder reactors, it is necessary to be able to control the temperature of the superheated steam or reheated steam within a range of approximately 5.degree. to 10.degree. F, if the turbines are to operate properly.
Large liquid metal control valves are considered beyond the present state of technology, and to develop the proper reliability in such valves would take an expensive research and development program. Temperature control could also be provided by controlling the output of the circulating or pumping devices; however, such controls would be expensive and increase the complexity of these devices and reduce their reliability.